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Latest COVID-19 Shots Boost Protection Against Infection Symptoms By 54 Percent

Despite promising early data, uptake of the vaccine remains low.

Laura Simmons - Editor and Staff Writer

Laura Simmons

Laura Simmons - Editor and Staff Writer

Laura Simmons

Editor and Staff Writer

Laura is an editor and staff writer at IFLScience. She obtained her Master's in Experimental Neuroscience from Imperial College London.

Editor and Staff Writer

Edited by Maddy Chapman

Maddy is a Editor and Writer at IFLScience, with a degree in biochemistry from the University of York.

vials of COVID-19 vaccine against a green background

The vaccines were updated in September 2023 in an effort to combat newer variants of SARS-CoV-2.

Image credit: Viacheslav Lopatin/

Early data from the Centers for Disease Control and Prevention (CDC) suggest that the latest round of COVID-19 shots are 54 percent effective at preventing symptomatic disease. The updated vaccines offer protection against the JN.1 variant that’s currently dominating worldwide, and yet uptake continues to be low.

“Everything from this study is reassuring that the vaccines are providing the protection that we expected,” lead author Ruth Link-Gelles, head of the CDC’s vaccine effectiveness program for COVID and respiratory syncytial virus (RSV), told CNN.


The data for the study were collected from 9,222 individuals who took COVID tests at a CVS Pharmacy or Walgreens location through the CDC’s Increasing Community Access to Testing (ICATT) program, between September 21, 2023, and January 14, 2024.

While the CDC’s stated aim with its COVID vaccination effort is to prevent severe disease that can cause hospitalization and death, Link-Gelles explained to CNN that measuring the impact on symptomatic disease is a good early indicator of the success of a vaccine. There’s a larger population of people who get infected than who are hospitalized with more serious illness, so you have more data to play with.

“That’s a really nice feature of this analysis, that it checks that box: Yes, the vaccine is working, it’s providing protection, it’s providing protection for JN.1, which is the current most common variant,” she said.

The 54 percent figure is broadly in line with what we’ve seen with previous COVID vaccines and with early data from other countries, Link-Gelles told the Associated Press. A recent study in The Lancet Respiratory Medicine also suggested that vaccination “consistently reduced the risk of long COVID symptoms”, highlighting the potential of these interventions beyond even the acute disease phase.


As we know, the protection from the vaccines doesn’t last forever. The CDC recommends that all adults and children over the age of 6 months receive a dose of the updated vaccine for maximum protection, even those who got their vaccines and boosters earlier in the pandemic.

In reality, however, the uptake has been limited. At the time of writing, 21.8 percent of US adults and 11.1 percent of children had reported receiving an updated shot. This is in contrast to the figures for flu vaccine coverage, which for adults nationally (including Puerto Rico) sat at 46.7 percent as of January 13.

Different health authorities have different recommendations around who should get a COVID vaccine and how often. In the UK, for example, only people who meet certain eligibility criteria have been offered a vaccine this winter, and the shots are not currently available for people to pay for privately. Once again, uptake has been lower than authorities would like, with data from frontline health staff showing that only 21.8 percent had received a COVID booster by November 2023, while only 39 percent had been vaccinated against the flu.  

The number of people dodging the vaccines has sparked concerns about the impact of increased staff sickness on health services already struggling with winter pressures, as well as the risk to vulnerable people from a COVID-19, flu, and RSV “tripledemic”.


On the flip side, the UK’s policy of running vaccination campaigns for COVID only in seasonal cycles has led to concerns that some with increased vulnerability to severe disease will be left without adequate protection for long periods of time if they can't access a vaccine.

If a vaccine is available in your area, the message from health experts is clear: keeping up to date with COVID-19 shots remains the best way of limiting the impact of the virus – which has not gone away – on ourselves and our wider communities.

The study is published in the CDC’s Morbidity and Mortality Weekly Report.


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